Download Community Ecology - Columbia University

Community Ecology - Module 5
Dr. James Danoff-Burg
Columbia University
Community Ecology
• Next step up the ecological hierarchy
from populations
• Definition: A population of species cooccurring populations
• Together, they comprise the biotic
component of the ecosystem
Community Function
• More than a Collective properties of
participant species
• Emergent properties
– ecosystem stability
– limits to similarity of competing species
Community Drama Players
• Producers (Module 6)
– Primarily plants and bacteria
• Consumers (Module 7)
– Herbivores, Predators, Parasites,
Parasitoids, Mutualists
• Decomposers (Module 8)
– Vertebrates, Invertebrates, Fungi, Bacteria
Community Features
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Richness
Abundance
Diversity
Evenness
Community Similarity
Trophic Levels
Feeding Guilds
Endemism
Vertical Structure
Community Features
• Richness
– number of species
• Abundance
– number of individuals
– either per species or gross abundance
Richness and Abundance
• Most commonly used features of
community for summarizing
• Most intuitive
BUT
• Could provide misleading results
• Why?
Problems w/ Richness &
Abundance
• Edge species are often invasive/exotic,
anthropophilic, and are everywhere
• May lead people to conserve areas that
are less important
• Do not take into account endemicity
Other Community Features
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Trophic Levels
Feeding Guilds
Evenness of species
Community Similarities
Vertical & Horizontal Structuring
Diversity (next most commonly used)
Diversity Indices
• Definition
– Combination of richness & abundance,
combine these data in different fashions
– Information Theory based (assessing
certainty of sampling all species present)
• Sensitivities
– Unevenness in abundance often leads to
strange results (e.g., deer herbivory study)
– Unequal collecting effort
Diversity Indices
• Methodology
– enter data, calculate indices
– general comparison of relative sizes
– some advocate for parametric statistics
• Common Indices
– Shannon-Wiener
– Simpson
– Brilluoin
– Fisher’s alpha
Today’s Activity - Brazil
• What is the influence of plant
biodiversity in home gardens on that of
beneficial and harmful insects?
• Could advocate for intercropping, a
more sustainable form of farming
Methods
• Sample insects using pan traps (water,
salt, soap)
• Use three home gardens of different
overall plant biodiversity
Methods II
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Remove insects from pan traps
Isolate parasitoids
Isolate homopterans
Sort both to morphospecies
Total richness and abundance
Input into computer program
Calculate diversity indices
Methods III
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Compare plots to each other
Make bar graphs of values and indices
Use photos: sites, process, and animals
Write up a paper of the class
Use PowerPoint
Football at 5:30